Had Nate Freiman not been in the A’s starting lineup Sunday, he might have dozed off in Oakland’s dugout.

The first baseman took a redeye cross-country flight Saturday night that landed in Miami early Sunday morning. A few hours later, and operating on zero sleep, Freiman delivered a three-run homer that provided the difference in the A’s 4-3 victory over the Marlins that completed a three-game sweep.

With that, the A’s reached the season’s halfway point in style, finishing their 81st game with a Major League-best 51-30 record. That represents the third-best record after 81 games in Oakland history.

They can thank their 6-foot-8 first baseman for delivering victory No. 51. Freiman got word Saturday night that he would be promoted from Triple-A Sacramento to take the roster spot of right fielder Josh Reddick, who went on the 15-day disabled list with a strained right knee.

He arrived in plenty of time for manager Bob Melvin to insert him in the lineup. Freiman came up with two men on and the game tied 1-1 in the sixth. Marlins starter Andrew Heaney left a fastball in his wheelhouse and Freiman turned on it and cleared the left field wall.

Tommy Milone went seven innings to get the victory for Oakland, and Ryan Cook notched his first save of the season.

Starting pitching report

Milone (6-3) turned in a steadying effort for a starting rotation that carried a 6.14 ERA over the previous 11 games. He lasted seven innings, gave up just four hits and three runs (two earned). He struck out three and walked two.

Bullpen report

Melvin said that he would be down a couple relievers after Saturday’s 14-inning marathon. He gave closer Sean Doolittle the day off and Cook – who has previous closer experience with Oakland - stepped in and finished it out in the ninth. Fernando Abad pitched the eighth after Milone exited.

At the plate

Freiman’s three-run shot summed up the A’s offensive M.O. over the first half of the season. They entered Sunday ranked second in the majors with 45 home runs with runners on base. They rank fourth in overall homers, but more importantly, they clear the fences when they’ve got men on.

Oakland trailed 1-0 entering the top of the sixth. Alberto Callaspo and Yoenis Cespedes singled in back-to-back at-bats. Then Josh Donaldson, who had the game-winning single in Saturday’s victory, hung tough on a good curve from Heaney (0-3) and delivered an RBI single to make it 1-1. Then Freiman unloaded on a first-pitch fastball from Heaney and sent his three-run homer over the left field wall.

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In the field

Milone, probably the best hitting pitcher on the A’s staff, also showed some nifty defensive skills Sunday. He ended the second inning with a terrific play covering first, when he managed to scoop a short-hop throw from second baseman Alberto Callaspo and simultaneously keep his foot on the bag to get the out.

Milone didn’t help himself with a man on second in the next inning. He fielded Christian Yelich’s comebacker, but instead of catching Jeff Mathis in a rundown, he threw to second and allowed Mathis to break for third safely. No matter, as the next hitter, Reed Johnson, smoked a liner up the middle that Milone snared and then threw to first to double off Yelich.

But Milone also got a big assist in the seventh from second baseman Alberto Callaspo. With the tying run on first base, Callaspo ranged left to make a diving stop of Jeff Mathis’ grounder and threw to first to end the inning.